Some studies have shown that Asian ginseng may lower blood glucose. Other studies indicate possible beneficial effects on immune function.

To date, research results on Asian ginseng are not conclusive enough to prove health claims associated with the herb. Only a handful of large clinical trials on Asian ginseng have been conducted. Most studies have been small or have had flaws in design and reporting. Some claims for health benefits have been based only on studies conducted in animals.

National Center for Complementary and Alternative Medicine (NCCAM) supports studies to better understand the use of Asian ginseng. Areas of recent NCCAM-funded research include Asian ginseng's interactions with other herbs and drugs and the herb's potential to treat chronic lung infection, impaired glucose tolerance, and Alzheimer's disease.

When taken by mouth, ginseng is usually well tolerated. Some sources suggest that its use be limited to 3 months because of concerns about the development of side effects.

The most common side effects are headaches and sleep and gastrointestinal problems.

Asian ginseng can cause allergic reactions.

There have been reports of breast tenderness, menstrual irregularities, and high blood pressure associated with Asian ginseng products, but these products' components were not analyzed, so effects may have been due to another herb or drug in the product.

Asian ginseng may lower levels of blood sugar; this effect may be seen more in people with diabetes. Therefore, people with diabetes should use extra caution with Asian ginseng, especially if they are using medicines to lower blood sugar or taking other herbs, such as bitter melon and fenugreek, that are also thought to lower blood sugar.

Tell your health care providers about any complementary and alternative practices you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care.

Asian ginseng may also inhibit blood clotting. Don't use ginseng if you are already taking anticoagulants or antiplatelet drugs such as clopidogrel (Plavix®).